According to the printed publication, "Triggerbare Hochleistungsschalter" [Triggerable Heavy-Duty Circuit Breakers] from "Physik in unserer Zeit" (1991), 4, pages 156 to 164, triggered switching of high current pulses, e.g., 10-100 kA, and long duration, e.g., up to 100 .mu.s, at voltages above 10 kV with low pressure gas discharge switches (e.g., thyratron, ignitron, pseudospark switch) is used, for example, in pulsed high-power lasers, in fusion and acceleration technology, in medical engineering and in materials processing. The high charge transfer rates of up to 10 As per switching operation required for these switching operations results in a high local thermal load on the electrodes of the switch, since in most cases the plasma remains in the close vicinity of its firing point and consequently only a spatially limited segment of the electrodes are used for generating and maintaining the necessary dense plasma. This thermal load results in an increased erosion of electrode material, which finally results in a severely limited service life of the switches.
Triggered switching of long current pulses has been achieved with low pressure gas discharge switches. In this connection, up to approximately 10.sup.8 switching operations and consequently usual service lives were obtained with the pseudospark switch, for example. Depending on the design, a very long service life can be obtained with the ignitron; however, it has important disadvantages in relation to the pseudospark switch: Lower rate of current rise, e.g., &lt;10.sup.10 A/S compared with .apprxeq.10.sup.12 A/S for the pseudospark switch, high sensitivity to voltage reversal and to excessively high ambient temperatures as well as the hazards to the environment that arise when the mercury used as the electrode material is released when the switch is shattered.
Japanese Patent Application No. 51-59851 describes a means for generating a magnetic field superimposed on the discharge in a gas discharge switch. In particular, an axial magnetic field is superimposed on the arc discharge by an appropriate design of the current paths.
Concepts for generating magnetic fields specially superimposed on a switching arc are known from vacuum switching technology. Slotting the pot-shaped supply leads to the contacts results in magnetic fields acting on the switching plasma, which either ensure that the contraction of the plasma is counteracted and the plasma remains diffuse, as in the case of the axial field contacts according to European Patent No. 0 155 376 B1 or that the plasma, as a constricted arc, is set in rotational motion, as in the case of the radial field contacts described in German Patent No. 34 26 323 B1. The latter can also be achieved by slotting the electrode surfaces, by which the so-called spiral contacts are defined. In doing so, three to six slots, for example, are made in the electrodes. Driven by the Lorentz force, the switching arc proceeds on a nearly circular path.
In a similar manner, U.S. patent application No. 3,280,286 brings about the formation of current paths for generating a radial field by slotting the switch contacts.